wsm1 wsm2 WSM3 power rating at 70? watts 1 2 3 resistance range ohms 0r01 to 1k 0r01 to 2k 0r01 to 3k limiting element voltage volts 100 tcr ppm/? < 1 ? : 100 < 1 ? : 100 .03 ? 700 0.1 ? : 200 1 ? : 20 1 ? : 20 10r 100 >10r 20 resistance tolerance % *1, 2, 5, 10 standard values e24 preferred ambient temperature range ? -55 to 155 moulded surface mount wirewound resistors wsm series ideal for automatic pick and place direct replacement for axial resistors all welded construction general note welwyn components reserves the right to make changes in product specification without notice or liability. all information is subject to welwyn s own data and is considered accurate at time of going to print. ?welwyn components limited ?bedlington, northumberland ne22 7aa, uk telephone: +44 (0) 1670 822181 ?facsimile: +44 (0) 1670 829465 ?email: info@welwyn-tt.com ?website: www.welwyn-tt.com electrical data issue c ?04.03 a subsidiary of tt electronics plc welwyn components 45 dimensions (mm) type l max i nom w max w max h max wsm1 7.9 2.54 7 4.2 3.94 wsm2 12 3.1 10.5 6.6 5.5 WSM3 18 3.1 16 7 6.5 type a b c d wsm1 2.9 2.6 2.8 8.1 wsm2 3.4 4.0 6 14 WSM3 3.4 4.5 11 20 physical data recommended pad sizes l w w i h b c d a marking wsm resistors are legend marked with type value and tolerance. wsm1 resistors are marked with value and tolerance. solvent resistance the body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits. construction a high purity ceramic substrate is assembled with interference fit end caps to which are welded the terminations. the resistive element is wound on the substrate and welded to the caps. the unit is then moulded. flammability the resistor coating is a flame retardant epoxy to ul 94. *note 5% or 10% preferred below 0.1 ohms wsm_c.qxd 29/4/03 10:38 am page 1
moulded surface mount wirewound resistors wsm series ?welwyn components limited bedlington, northumberland ne22 7aa, uk telephone: +44 (0) 1670 822181 ?facsimile: +44 (0) 1670 829465 ?email: info@welwyn-tt.com ?website: www.welwyn-tt.com 46 issue c ?04.02 welwyn components physical data dimensions (mm) ao bo ko w p t po wsm1 4.2 7.62 4.2 16 8 0.36 4 0.1 wsm2 6.75 11.95 5.22 24 12 0.36 4 0.1 WSM3 7.3 18.3 6.7 32 12 0.4 4 0.1 all other dimensions as per eia481 standard wsm1 wsm2 WSM3 load at rated power: 1000 hrs @ 70? ? r% 2 0.001 ? 2 0.001 ? 3 0.001 ? dry heat 1000 hrs @ 155? ? r% 2 0.001 ? 2 0.001 ? 3 0.001 ? short term overload ? r% 2 0.001 ? derating from rated power @ 70? zero at 155? moisture ? r% 1 0.001 ? 1 0.001 ? 1.5 0.001 ? temperature cycling ? r% 1 0.001 ? resistance to solder heat ? r% 1 0.001 ? isolation voltage v 1,000 insulation resistance ohms >1000m substrate bend ? r% 0.2 0.001 ? performance data note: the power ratings to be applied depend upon the board used and the ambient temperature. wsm_c.qxd 29/4/03 10:38 am page 2
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